April 8, 2011

The Dangers of Elephant Relocation

Today sees the theatrical release of the documentary Born to be Wild 3D, which chronicles the rescue and rehabilitation of orphaned animals. The story move back and forth between primatologist Dr. Birute Galdikas, caring for orangutans in Borneo, and "celebrated elephant authority" Dame Daphne Sheldrick, caring for, well, elephants in Kenya. Like most IMAX nature films these days, Born to be Wild 3D goes to the third dimension, but, unlike more commercial 3D movies, the 40-minute film is getting good reviews from critics.

Of course, as Galdikas and Sheldrick would no doubt tell us, the work does not end when animals are re-released or relocated, as introducing a population to a new area can have unexpected consequences. In the 1990s, employees at Pilanesburg National Park in Mogwase, South Africa discovered that white rhino deaths doubled or even tripled in 1992, 1994, and 1996. (The southern white rhino nearly went extinct before a successful anti-poaching campaign in the 1960s and 1970s, and still only has a population of around 17,000.) Examination of the carcasses showed that the increased mortality rate was due to the park's elephants, who normally do not pursue rhinos. A 2001 paper by Gus van Dyk of the Pilanesburg National Park and biologist Rob Slotow of the University of Natal in Durban found that the elephant population had been translocated after a "culling" of the elephants at another park, and was introduced to Pilanesburg without adult males. As a result, van Dyk and Slotow say, the young adult males entered musth--an annual period of heightened testosterone and increased sexual activity and aggressiveness--"about 10 years younger than expected" and stayed in musth "for abnormally long periods (3-5 months) for such young animals." Fortunately, in 1998 six older males were introduced from another parkl; at the time the paper was published, the musth periods of the "orphan" Pilanesburg elephants had shown "a significant reduction," and white rhino deaths returned to normal.